Updated

The mother of a 13-year-old boy convicted in the fatal stabbing of a 9-year-old at a Michigan playground has been found guilty of abusing her son.

A Grand Rapids jury convicted the 39-year-old woman Friday of child abuse. The boy was found guilty of first-degree murder this month. His stepfather also has been convicted of abusing him.

There was no dispute the boy, who was 12 at the time, killed Michael Connor Verkerke in August 2014 in Kentwood, near Grand Rapids. The jury in that case rejected defense claims that a childhood of abuse should shield him from criminal responsibility.

He will be sentenced as a juvenile, then resentenced as an adult when he turns 21.

The Associated Press isn't naming the boy or relatives because of his age.